MIMO Precoder Design via Slack Variable Sub-problems

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Solution Overview

Problem

Current technologies lack direct and effective solutions for optimizing precoder design in multiple-input and multiple-output (MIMO) interference networks, especially under channel uncertainty, which hinders the maximization of weighted sum-rate and max-min rate objectives.

Innovation Solution

The method introduces a slack variable to transform these objectives into solvable sub-problems, using convex optimization and the Schur complement to convert inequalities into linear matrix inequalities, ensuring convergence and efficient computation of transmit precoders for both perfect and imperfect channel state information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If linear transmit precoding and decoding schemes are used, then degrees of freedom optimality is achieved, but direct solvability for weighted sum-rate and max-min rate objectives is lost

Engineering Contradiction:

Improvedegrees of freedom optimalityVSAvoiddirect solvability

Core Design Contradiction:

ProductivityVSEase of operation

Solution Approach 1:

The patent segments the original non-convex optimization problem into multiple convex sub-problems by introducing slack variables. The weighted sum-rate maximization and max-min rate maximization are divided into separate sub-problems that can be solved iteratively, with each sub-problem being convex and directly solvable while maintaining overall optimality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs an iterative algorithm that dynamically updates precoder and receiver filter designs across multiple iterations. The slack variables are updated in each iteration based on the current channel estimates and interference conditions, allowing the system to adaptively converge to the optimal solution while maintaining computational tractability.

Inventive Principle:

Principle #15Dynamics

2Reliability

If channel uncertainty is considered, then robustness is improved, but solution tractability deteriorates

Engineering Contradiction:

Improverobustness under channel uncertaintyVSAvoidsolution tractability

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent performs preliminary actions by obtaining channel estimates and computing initial slack variables before the main iterative optimization. The receiver filters are designed based on estimated channels in advance, and these preliminary designs serve as starting points for the iterative refinement process, reducing the complexity of handling channel uncertainty during optimization.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback mechanisms where the slack variables are updated in each iteration based on the current precoder and receiver filter designs. The channel uncertainty is continuously accounted for through feedback from the received signals, allowing the system to adapt to channel variations while maintaining solution tractability through the convex structure of the sub-problems.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8660202B2Robust precoder and receiver filter design for Gaussian interference channel

Publication Date: 2014.02.25 NEC CORP

AI summary

A system and method for providing at least one transmit precoder includes transforming at least one of a weighted sum-rate and max-min rate objective into two or more sub-problems by introducing at least one slack variable. The two or more sub-problems are iterated on a computer readable storage medium to provide at least one transmit precoder for each transmitter.